Carburetor control mechanism



Jan. 6, 1953 G. c. FRICKE ET AL 2,624,325

CARBURETOR CONTROL MECHANISM v Filed July 1, 1950 2 swans-swam 1 MINVENTOR. 50 60) c. F/P/CA:

34 04 W0 J 56%4/75 4 BY Jan. 6, 1953 G. c. FRICKE ET AL 2,624,325

CARBURETOR CONTROL MECHANISM Filed July 1 1950 2 SHEETS-SHEET 2INVENTOR. 60) c. PIP/6K5 By any/0 swarm? WMW A /mm) Patented Jan. 6,1953 CARBURETOR CONTROL MECHANISM Guy 0. Fricke and David J. Schaifer,Detroit,

Mich, assignors to Bendix Aviation Corporation, South Bend, Ind., acorporation of Delaware Application July 1, 1950,.Serial No. 171,626

'9 Claims.

The present invention relatesto a control'for anengine, and moreparticularly to an automatic choke control for a carburetor of aninternal combustion engine.

One of the principal objects of the present invention is to provide .afuel enrichment device for. aninternal combustion engine which variesthe fuel-air ratio in accordance with variations in the temperature ofthe cooling fluid of the engine.

Another .object'of the invention is to provide a control for the :chokevalve of a carburetor which .is responsive to manifold vacuumand tovariations .in .the .temperature of the liquid in the cooling system ofthe engine.

Another object is to provide a choke control device for an engine whichis readily responsive to a temperature of some part of the engine remotefrom said device.

A further object is to provide a choke control device which varies thefuel-air ratio in accordance with the engine requirements.

Additional objects and advantages of the present invention will becomeapparent from the following description and accompanying drawings,wherein:

Figure 1 is a side elevation of a multiple cylinder internal combustionengine showing schematically certain elements of the present invention;

Figure 2 is a vertical cross-sectional view of our choke control device;

Figure 3 is a sectional view of our control device taken on line 33 ofFigure 2;

Figure 4 is a sectional view of the control device taken on line 4-4 ofFigure 3;

Figure 5 is-a sectional view of a modified form of our invention; and

Figure 6 is asectional view'of a'temperature responsiveswitch for ourchoke control device.

:Referring -more specifically .to the drawings, and to Figure .1 inparticular, wherein a multiplecylinder water 20001601 internalcombustion engine .is shown, numeral 4 ii designates a cylinder block,[2 acylinderhead, M an intakeman-ifold, l6 a'carburetor, 18 an aircleaner mountedon saidrcarburetor, and :20 our choke-control device.mounted in operative position on the air horn of the carburetorand-connected byan electrical circuit with a battery 22, anignitionswitch 24 and a thermostatically controlled switch unit 26mounted on cylinder .head !2. For the purpose of this description, theengine, including the carburetor, may be considered conventionalinconstruction and operation.

The choke control mechanism is encased in a housing 30 secured to thecarburetor air horn 32 adjacent one end of the choke valve shaft 36 onwhich choke valve 36 is mounted in the carburetor induction passage 33,said choke valve preferably being of the unbalanced pressure responsivetype or having a poppet valve adapted to permit an increase in air flowas soon as the engine begins to fire. Shaft 34 extends into the housingand is rotated in the choke opening direction by a vacuum responsivepiston 40 connected to said shaft by a rod 42 and a lever 44 rigidlymounted on one end of said shaft. Piston 4D 'is'adapted to reciprocatein a cylinder 46 in response to'manifold vacuum transmitted to saidcylinder through conduits it and 50 and a port 52 from the inductionpassage on the engine side of the throttle valve. The degree of manifoldvacuum required to actuate the choke valve is partially controlled by anair bleed passage'54 extending longitudinally through piston in andconnecting cylinder 46 with the internal portion of housing 30, which inturn is vented to the atmosphere through port 56 in cover 58.

The choke Valve is held closed during engine cranking and is urgedtowards closed position during "the warming-up period by a solenoid 6i]actingthrough a lever 62, a coil spring 64 and. lever 44, said springbeing mounted on the end of choke shaft 34 and connected at one end tolever44 and at the other end to lever 62 to form a'resilientlinkagebetween the choke valve and solenoid 60. Lever 62 is pivoted at one endon a pin 66 secured in the wall of housing 30 and is preferablyconstructed of soft steel with a thin plate of copper on the lower sideat the point of contact between the lever and the solenoid core 68..Lead .10 connects the solenoid with thermostatic switch 26 and lead i2connects the solenoid with any suitable ground, such as the main body orthe airhorn of the carburetor.

The thermostatic switch unit 26, shown in detail in Figure 6, is inseries with the ignition switchand is adapted to control the choke uniton carburetor IS in response to changes in the temperature 'of theengine cooling liquid. The switchis contained in a-cap at of plastic orother nonconducting material and consists of a fixed contact 82 mountedon stem 84 which is secured in the side wall of said cap, and a movablecontact 86 mounted on a leaf spring element 88 which is secured byscrews E39 and 92 to the inside wall of the cap opposite stem 84,contact 82 being connected by a lead 94 with the ignition switch 24andbattery 22, and contact being connected by lead Hi with solenoid 66. Thebase it of the switch unit is adapted to be secured to the cylinder headof the engine, preferably threaded into a hole therein, and contains achamber I02 filled with a thermo-expansible material, such ashydrocarbon and copper. A yieldable diaphragm I04 forms the upper wallof chamber I02 and is operatively connected to switch element 88 by ashaft I06 abutting against the upper side of said diaphragm and a stemI08 urged in the direction to permit the switch to close by a coilspring I I9 reacting between a fixed sleeve H2 and a flange II 4 on thelower end of the stem. The upper end of stem I08 is insulated fromelement 88 by a plastic cap H6. As the engine cooling liquid becomeswarm after the engine starts, the heat is transmitted to thethermo-expansible material in chamber I02 which urges diaphragm I04upwardly, forcing stem I08 to move contact 86 on element 88 away fromcontact 82, thus interrupting the current from battery 22 to solenoid60.

In the starting operation of a cold engine, turning on of the ignitionswitch 24 completes the circuit for the choke unit on the carburetor inthat switch unit 26 is always closed when the engine is cold. Thesolenoid 00, which is then energized, pulls lever 62 to the right, asshown in Figure 3, rotating spring 64 and the choke shaft 34 in theclockwise direction to close the choke valve for starting. As soon asthe engine begins to fire, the air flow in the induction passage 38 ofthe carburetor causes the choke valve (if the valve is of the unbalancedtype) to open slightly against the force of spring 64 to providesufficient air for the operation of the engine before the manifoldvacuum has increased sufiiciently to operate piston 40. When thethrottle valve is moved toward closed position and the manifold vacuumhas, as a result, increased substantially, piston 40 moves downward incylinder 26, urging the choke valve in the opening direction inopposition to the yieldable force applied by solenoid 60 through spring64, The degree to which the choke valve will be opened by piston 40depends upon the size of port 52 relative to passage 54, upon thestrength of spring 64, and upon the degree of manifold vacuum. The firsttwo factors can be adjusted to suit requirements. If the throttle valveis-again opened to the point where the manifold vacuum can no longerhold piston 40 down in opposition to the solenoid, the choke valve movestoward closed position and provides additional fuel enrichment forengine acceleration. As the air flow increases with acceleration, theunbalanced valve partially opens to provide the air required for thehigher speed. When the cooling liquid has reached a predeterminedtemperature, thermostatic switch 26 opens the choke circuit,de-enerizing solenoid 60 and permitting the choke valve to move to wideopen position for normal engine operation.

In Figure 5, a modification of our choke control device is shown whereina solenoid I20 and a vacuum piston I22 are on opposite sides of lever44. The solenoid 120 actuates a metallic piston I24 which is connectedto lever 44 by a coil spring I26. Piston I22 is connected to lever 44 bya rod I28. The cylinder 630 in which piston I 22 reciprocates isconnected to the induction passage through a port I32 and conduitssimilar to conduits 48 and 59 shown in Figures 1 and 2. The operation ofthe choke control device employs an electrical circuit and athermostatic switch similar to that shown in Figures 1 and 6.

Although thermostatic switch 26 is shown mounted on the engine cylinderhead, it may be mounted at any other suitable point in the coolingsystem of the engine or at some other point on the engine apart from thecooling system, as for example the exhaust manifold, which will indicatethe operating temperatures of the engine.

The thermostatic switch may be of the design shown in Figure 6 or anyother suitable design. Other modifications may be made in our chokecontrol device to suit requirements without departing from the scope ofthe present invention.

We claim:

l. A control for an engine carburetor having a choke valve and a shaftfor said valve, comprising a lever on said shaft, a solenoid for urgingsaid valve toward closed position, a member actuated by said solenoid, ayieldable means connecting said member to said lever, a vacuumresponsive means connected to said lever for urging said valve in theopening direction, a circuit for said solenoid, and a means responsiveto some engine temperature for controlling the current through saidcircuit.

2. A control device for the choke valve of an engine carburetor,comprising a solenoid, a yieldable linkage operatively connected to saidvalve and adapted to be actuated by said solenoid in the direction toclose said valve, and a vacuum responsive means connected to said valvefor urging said valve in the opening direction on an increase ofmanifold vacuum.

3. A control device for the choke valve of an engine carburetor,comprising a solenoid, a resilient linkage, operatively connected tosaid valve and adapted to be actuated by said solenoid in the directionto close said valve, a vacuum responsive means connected to said valvefor urging said valve in the opening direction on an increase ofmanifold vacuum, a circuit for said solenoid, and a switch meansresponsive to some engine temperature for controlling the currentthrough said circuit.

4. A control device for the choke valve of a carburetor for a liquidcooled engine, comprising a solenoid, a yieldable linkage operativelyconnected to said valve and adapted to be actuated by said solenoid inthe direction to close said valve, a vacuum responsive means connectedto said valve for urging said valve in the opening direction on anincrease of manifold vacuum, a circuit for said solenoid, and a switchmeans responsive to the temperature of the coolingliquid for controllingthe current through said circuit.

5. A fuel enrichment device for an internal combustion engine having aninduction passage and a carburetor with a throttle valve, a choke valveand a shaft therefor, comprising a lever secured to said shaft, asolenoid, a pivoted lever actuated by said solenoid, a yieldable meansconnecting said first mentioned lever with said second mentioned lever,and a chamber connected to the induction passage on the engine side ofthe throttle valve and having a movable wall connected to said firstmentioned lever.

6. A fuel enrichment device for an internal combustion engine having aninduction passage and a carburetor with a throttle valve, a choke valveand a shaft therefor, comprising a lever secured to said shaft, asolenoid, a pivoted lever actuated by said solenoid, a resilient meansfunctionally interposed between said levers, a chamber connected to theinduction passage on the engine side of the throttle valve and having amovable wall, a rod connecting said wall with said first mentionedlever, and a circuit for energizing said solenoid.

'I. A fuel enrichment device for an internal combustion engine having aninduction passage and a carburetor With a throttle valve, a. choke valveand a shaft therefor, comprising a lever secured to said shaft, asolenoid, a pivoted lever actuated by said solenoid, a spring connectingsaid first mentioned lever with said second mentioned lever, a cylinderconnected to the induction passage on the engine side of the throttlevalve, a piston in said cylinder connected to said first mentionedlever, a circuit for said solenoid, and a means responsive to someengine temperature for controlling the current through said circuit.

8. A fuel enrichment device for an internal combustion engine having acarburetor with a choke valve and a shaft therefor, comprising 'a leversecured to said shaft, a solenoid, a pivoted lever actuated by saidsolenoid, a yieldable means functionally interposed between said levers,a chamber having a movable wall adapted to be subjected to manifoldvacuum, a rod connecting said wall with said first mentioned lever, anda thermo-statically controlled switch responsive to an enginetemperature for controlling said solenoid.

9. A fuel enrichment device for a liquid cooled 25 internal combustionengine having an induction passage and a carburetor with "a throttlevalve, a choke valve, and a shaft therefor, comprising a lever securedto said shaft, a solenoid, a pivoted lever actuated by said solenoid, aspring connecting said first mentioned lever with said second mentionedlever, a cylinder connected to the induction passage on the engine sideof the throttle valve, a piston in said cylinder connected to said firstmentioned lever, a circuit for energizing said solenoid, and athermostatically controlled switch in said circuit responsive to thetemperature of the cooling liquid of the engine.

GUY C. FRICKE.

DAVID J. SCI-IAFFER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,605,165 Brotz Nov. 2, 19261,913,131 Sisson June 6, 1933 2,071,633 Hunt Feb. 23, 1937 2,158,424Hunt May 16, 1939 2,377,248 Langhaar May 29, 1945

